Avaliação do desempenho do formato de 2-hidroxietilamônio como inibidor de corrosão acelerada por escoamento (FAC) em aço carbono

Abstract

Flow-Accelerated Corrosion (FAC) represents a critical challenge for the integrity of carbon steel pipelines in the oil and gas sector, with the application of corrosion inhibitors being one of the primary methods employed for its mitigation. This work evaluated the performance of the protic ionic liquid (PIL) 2-hydroxyethylammonium formate as an inhibitor for 1020 carbon steel in a saline medium, consisting of a 3.5% NaCl solution under continuous flow. For the experiments, a closed-loop system (flow loop) with one-inch PVC piping was used, operating at a flow rate of 650 L/h. Tests were conducted at temperatures of 25, 35, 45, and 55 °C, at intervals of 4, 8, and 12 h. The inhibitor's efficiency at a concentration of 500 ppm and the assessment of surface wear were investigated through gravimetric techniques and Computational Fluid Dynamics (CFD), complemented by optical microscopy (OM) and X- ray diffraction (XRD). The system's hydrodynamics proved to be a determinant factor in the degradation rate; CFD simulations indicated that samples subjected to parallel flow experienced higher shear stresses, accelerating both mechanical and chemical wear. The inhibitor showed low resistance to shear stress at ambient temperatures, with efficiencies lower than those reported in static regimes. The best efficiency, 70.14%, was achieved at 45 °C, possibly due to a transition in the adsorption mechanism from physical to chemical, making the protective film more robust. XRD analysis identified lepidocrocite as the majority phase and evidenced that the inhibitor favored the formation of goethite, a more stable corrosion product. It is concluded that, although 2-hydroxyethylammonium formate demonstrates protective potential, its effectiveness under constant flow is highly dependent on temperature and the stability of the film formed, reinforcing the need for operational condition optimization to enable its use in dynamic industrial systems.